Electrochemical aptasensor for tumor necrosis factor α using aptamer–antibody sandwich structure and cobalt hexacyanoferrate for signal amplification

Abstract

This work suggests one method of electrochemical aptasensor, based on aptamer—tumor necrosis factor α (TNF-α)—antibody sandwich structure, which can be used for selective detection of TNF-α. The TNF-α aptamer as the capturing probe immobilized on the surface of cobalt hexacyanoferrate (CoHCF) and gold nanoparticles (AuNPs) modified graphite screen-printed electrode. Then a sandwich like structure was fabricated upon TNF-α protein using antibody conjugated to horseradish peroxidase (HRP) as the detection probe. The detection was performed by adding hydrogen peroxide and o-amino phenol as a probe system for HRP activity and then detected the response. Each step of the preparation of the immunosensor was monitored via electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Under optimum conditions and at a typical working as low as 0.05 V (vs. a silver pseudo electrode), the electrode works in the 1–100 pg mL− 1 TNF-α concentration range, with a 0.52 pg mL− 1 detection limit. This method was then applied to the determination of TNF-α in serum samples.